Responses of varying levels of DI .-methionine and TSAA and effects on ~(13)CMet and ~(13)CCys oxidation

摘要

As the industry moves towards antibiotic-free practices, it is important to understand the degradation of TSAA to the end-product of glutathione, which plays an important role in gut health. Two experiments were conducted to determine the pathways inwhich [l-~(13)C]Met or [l-~(13)C]Cys were metabolized. Birds were fed grower diets containing varying levels of TSAA in both experiments (Evonik AMTNOChick~R 2.0). At 21 d of age, birds were selected for infusion of [l-~(13)C]Met (Exp 1) or [l-,3C]Cys (Exp 2), indirect calorimetry, infusion of [l-~(13)C]NaHC03, or control. Blood and tissues were then collected 5-420 min post-infusion. Comparison of Met and Cys ~(13)C02 revealed differences in IG and IV infusions (P<0.05). Loss of [l-~(13)C]Met through oxidation in birds fed sufficient TSAA levels increased for IG infused birds (20.45 vs 10.21%; P<0.05), suggesting parenteral uptake allows more efficient delivery than enteral. Ultimately, the loss of the Met and Cys labels to ,3C02 proves worthy to understanding TSAA, considering greater ~(13)C02 production from [~(13)C]Met may signify increased cysteine synthesis. Cysteine, a non-essential amino acid, is involved in mucin production and gut health. Additionally, considering cysteine is a precursor forglutathione, greater cysteine synthesis can result in an increase in glutathione, and consequently, more protection to broilers.